Conversion of hydrocarbon oils



Patented July Z, 1940 UNITED STATES PATENT oFFice versal Oil ProductsCompany.,l

Chicago, Ill., a

corporation of Delaware Application April 30, 1937, Serial No. 139,884

8 Claims.

This kinvention particularly refers to an im;- proved process andapparatus" for the fractional distillation of hydrocarbon oils ofrelatively Wide boiling range, accompanied by thefpyrolytic Aconversionof selectedA low-boiling and intermediate fractions of the chargingstock under independently controlled heating conditions, treatment ofselected high-boiling fractions of the charging stock `in oommingledstate with hot conversion 1U products resulting from one or both of theaforementioned cracking operations and further conversion ofintermediate liquidl products of the cracking operation together Withsaid intermediate fractions of the charging stock. The process isoperated for the production of high vyields of good quality motor fueland minor yields of either liquid residue, such as good quality fuel, orpetroleum coke; the coking step, when employed, being assisted bydirectly commingling with the materials undergoing coking regulatedquantities of the highly heated conversion products resulting from thatstep of the lprocess to which said selected low-boiling fractions of thecharging stock are supplied.

2 5 lCnc of the important advantages of the invention resides inl theprovisionswhereby high-boiling fractions of the charging stock'recovered in the distilling operation may be subjected to appreciablecracking in a reaction chamber of the system by cominingling the sametherein with highly heated products resulting from conversion of theselected low-boiling and intermediate fractions of the charging stock,without `passingsaid high-boiling fractions of the charging stockthrough a cracking coil. .feature obviates the excessive formation ofAcoke and gas, which is often encountered in cracking such relativelyheavy oils in a heating cOiL'Without sacricing the additional yields ofgasoline which are obtainable by cracking said heavy fraction of thecharging stock.

Another advantageous feature of the invention resides inthe provisionswhereby the total intermediate liquid conversion products of the processare subjected, in commingled state, with 45 said selected intermediatefractions of the charging stock, `to conversion in the same heating.coil under more severe cracking conditions than those afforded theIhigh boilingy fractions of the charging stock. Except for this feature,the present invention is closely related to the process of my issuedUnited States 2,070,249, which discloses a combination topping andselective cracking system intermediwherein 5g ate andhigh-boilingcharging stock fractions are Patent No.

supplied from a distilling `step to the fractionator of a crackingsystem, their high-boiling components commingling therein withhigh-boiling fractions of the intermediate liquid conversion productsand being directed therewith to the reaction chamber -of the .crackingsystem, while their iovv-boiling components are passed, together Withselected low-boiling .fractions of the intermediate liquid products,`through a cracking coil into 'the `reaction chamber. 1 l vhave Vfoundthat Vitis often advantageous to subjectthe total 4reflui; condensate(intermediate liquid lconversion products) to the same 'crackingconditions alforded the intermediate fractions of the charging stock,since, 'With most types of charging stock, said reflux condensate (whichis the result ofinitial cracking of the charging stock or selectedfractions thereof) is more 4refractory to cracking than virgin chargingoil of similar boiling range characteristics and, therefore, the 20high-boiling fractions of said intermediate liquid products vrequiremore severe conversion conditions, to produce good quality gasoline,than do the high-boiling fractions of the virgin charging stock. fThepresent process is particularly directed to a specific improvement `overthe process disclosed in the aforementioned issued patent whereby 'thetotal intermediate liquid conversion products of the process aresubjected to further cracking in commingled state with selected inntermediate fractions of the lcharging stocky and under more severecracking conditions than those afforded the high boiling fractions ofthe virgin charging oil.

`The invention resides inthe cooperative` combination `between thevarious steps of the process, each lof which are interdependent andmutually contribute to vproduce the desired final results. The entireprocess may be conducted in `a relatively simple unied system and is.sufficiently 40 flexible in operation to permit the advantageoustreatment of practically any type of hydrocarbon oil of relatively wideboiling Arange to produce one or-.rnore types of gasoline and to produce"either good quality liquid residue or coke, as desired.

One specific embodiment of the invention comprises subjecting ahydrocarbon oil of relatively Wide boiling range, such as crudepetroleum,xfor example, to fractional distillation, whereby it isseparated into termediate and high-boiling fractions, recovering anycomponents of said low-boiling .fractions -Which boil Within the rangeof gasoline and are of satisfactory antiknock value, `subjecting anotherselected portion of said low-boiling 45.5

selected relatively low-boiling, in-

of the charging stock to independently controlled cracking temperatureat superatmospheric pressure, supplying resultant heated products tosaid enlarged reaction chamber, simultaneously supplying to saidreaction chamber said selected re1- atively high-boiling fractions ofthe charging stock, Without previously heating the same to crackingtemperature, whereby they are subjected to conversion in said reactionchamber inV commingled state with said hot conversion products suppliedthereto and by means of heat derived from the latter, separatingvaporcus and liquid conversion products resulting from the crackingafforded the commingled materials in said reaction chamber andsubjecting said liquid products to appreciable further vaporization atsubstantially reduced pressure, subjecting the vaporous conversionproducts, including those evolved by said further vaporization of theliquid products, to fractionation whereby their components boiling abovethe range of gasoline are condensed asrrefiux condensate, returning saidreflux con densate to the same cracking zone, preceding said reactionchamber, to which said intermediate fractions of the charging stock aresupplied, subjecting fractionated vapors of the desired endboiling pointto condensation and recovering the resulting products.

The accompanying diagrammatic drawing illustrates one specific form of,apparatus in which the improved process of the invention may beconducted.

Raw oil charging stock for the process, comprising crude petroleum orany other hydrocarbon oil of relatively wide boiling range whichpreferably contains an appreciable quantity of gasoline or gasolinefractions, all or a substantial portion .of which may be of inferiorantiknock value, is directed through line I and valve 2 to pump 3 bymeans of which it is fed through line 4 and valve 5 to heating coil Sand therein heated, by means of heat supplied from a furnace 7, to atemperature adequate to effect its substantial subsequent vaporizationand fractionation. The heated charging stock is directed from heatingcoil 6 through line 8 and valve 9 into distilling and fractionatingcolumn lil, wherein its separation into selected relatively low-boilinginterme diate and high-boiling fractions, is effected. It is, of course,also within the scope of the invention to heat the charging stock to thedesired .distilling temperature in any other well known manner, notillustrated, such alternative methods comprising, for example, indirectheat exchange betweenthe charging stock and relatively high intermediateor final products of, the cracking operation or, when desired, suchindirect heat exchange may be utilized in combination with the heatingcoil.

The loweboiling fractions of the charging stock may be recovered as oneor a plurality of streams from the distilling and fractionating column,provision being made for removing all or the lowest boiling portions ofthe/same as an overhead prodportion of the fractionator, directedthrough line I I and valve I2 to condensation and cooling in condenserI3, the resulting distillate and any uncondensed gases passing throughline I4 and valve I5 to collection and separation in receiver I6. Whenthe condensed gasoline or low-boiling gasoline fractherefrom throughline i1 and valve I 8 to storage or elsewhere, as desired. Anyuncondensed gaseous materials may be released from the receiver throughline I9 and valve 20. When the charging stock does not contain anysubstantial quantity of gasoline orlow-boiling gasoline fractions ofsatisfactory antiknock value, the total gasoline is preferably collectedany high-boiling gasoline fractlons of inferior later described, inheating coil 28.

Intermediate fractions of the charging stock comprising, for example,selected components thereof such from column I0 and kdirected throughline 23 and valve 3D to pump 3| by means of which they aresuppliedthrough line 32, valve 33 and line 62 to conversion in heatingcoil `34, as will be later described.

chamber 43, for further vaporization therein and wherein they may, whendesired, be reduced to coke or wherefrom their unvaporized componentsmay be recovered as residual liquid.

The oils supplied to heating therein `to the desired crackingtemperature, superatmospheric m'to.

.from :heating .coil through .line .45 and valve #Spintoreaction chamberVlill.

.The relatively low-.boiling voils supplied, as .pref Viously described,lto .heating .coil 28 `are heated "therein `preferably to a .highertemperature than ,that employed in heating coil 3.4,xpreferablyat -a`:substantial superatmospheric pressure, `:by .means of .heat suppliedto this zone from furnace 41. The conversion conditions maintained incoil `23 are preferably regulated'to effect va substantial .improvementin I the antiknock :value Vof .any gasoline or gasoline fractionssupplied vtherei-to, without excessively altering L their boiling rangeYsince :conditions withinthe reformingrange may This is commonly termedreformingand,

be so selected that they arealso suitablefor '.crackingnaphtha,keroseneior kerosene distillate andithellike, one or more oils of :thelatter type .may be included in 'low-'boiling V.oils A supplied 'to:heating v:coil V28, whereby to 'produce additional yields ofagoodquality fgasolineitherefrom.

The .highly heated conversion products are dis- .chargedfrom vheating'coil- 28 through .line 48 and vpreferably 'a substantial portion orallzof these products-are directedthrough line 4 9 andyalve 50 intoreaction chamber '40, although v a regulated portion or-all -oftheheated "products discharged fromheatinggcoil 28 may, when desired,

bedirected ,throughvalve 5 l in line Minto charnber 43, `particularly 1in case nhigh-boiling fractions :of :the charging stock from ,column IB.are Vsupplied tochamber 43 for reduction therein to coke. Chamber 40 isalso preferably operated fat `a Asubstantial superatmosphericpressure-which may be substantially thesameas that employedingthecommunicating heating l:coil `utilizing the lowest .pressure `or may besomewhat lower than that :employed in .either 'of :these heating coils.

ber from heating coil 28fand/ orheating coil 34 comminglein .this fzonewththe high-boiling .fractions of 'thecharging stock supplied theretoand'serve ,toheatthe latter to asuitable cracking temperature.

.The `heat ,exchange thuseiected in chamber 4B valso 'serves topartially 4cool "the heated @converssion products and prevent.theirexce'ssivezfurther Iconversion inthiszone. The conversion#afforded additionalquantities-of desirable lowiboiimg matemperature andpressureconditions .prevailing therein'and in 'the` particular case"herelillustrated, 'the commingled materials 'after .passing throughsubstantially the entirele'ngth of. the reaction chamber .are.removed'frorh thelower portion 'of this zone in .commingled statethrough line "52 and vdirected therefrom through-valve 53 vinto chamberd3. "It is, however, also 'withinth'e scope'of theinvention toseparately'remove vaporous and liquid .conversion `products jfrom Gh'a'inber'linfany wll known manner, not 'illustrated, and, when desired, provisionmay be 'na'de vfor .subjecting the various streamsy'of materials.supported'fto .this zoneo'r vaporous and" liquid components of the.several ,streams toidiierent .conditions vof .treatment in 'chamber 40,by the use of Isuitable wellkn wn .means such as wallwa'shing devicesvandthe like, -not illustrated, whereby segregation .of .the vaporousand liquid conversion vgproducts may be accomplished in .chamber Hl-.and/onbyintroducin Some or-.all of is accomplished. In case preferablyassisted b v of the system.

.line 54 controlled by valve into the chamber, when The ihotconversionproductsthus supplied to chamthe variousstreamsx-into .chamberBeat different points in this zone.

Chamber 43 is preferably ,operated -at la substantially reduced pressurerelative to that employed in vchamber 4 0, whereby appreciable-fur- 5ther yaporization of the .liquid conversion -fproducts supplied theretofrom` reaction chamber 4 0 hamber 43 is feuerated as a looking zone,,the coking operation is v introducing .regulated ..10

'quantities of the highly heated -fprodui f om the heating coil .28;intodirect Contactwiththe materials undergoing poking therein. The cokeproduced may be allowed to r:accumulate within chamber 43 until "thiszone is substantiallyrgiilled, 2,15

or until the operation lthereof is Aconjlp leted for any reason,following which `the -ehambenm y be cleaned and'prepared vvfor furtheroperation,

preferably after -it has .been isolatedffromthe -fr est Chamber 43 isprovided Wglh 120 58 --throush 'which liquid residue may -be remliedfromthechamber, when the-system is Operatedgfor the production Yof suchmaterial in this zone, and this line may :also serve as ya mea-ns `ofintroducing steam, water or other suitable cooling material j y thelatteris .operated as a ooking Zonato hastencooling fandfacilitateremoval of-the '-coke after the operation-,of

the chamber, is completed. Preferably, although .3o

only a single coking chamber is Aillustrated iii-the drawing, aplurality of such ,Zonesis preferably employed and the various cokingGhamberspreferably are alternately operated,r ,cleaned andprepared forfurther operation inforder that .this 35 stage, in .common with the restof ,the,systenn may be 'operated continuously.

The vaporous products evolved in ,chamber '43 are vdirected from theupper portion -tl'lereo'f through line 56 and valve '51 to fractnationin fractionator 58, whereby their components ilOil" n ing above therange of the desiredgasoline,prodm uct .of this stage `of the' system,are condensed as reflux condensate.

"Preferably, the 'total vrefluxy condensate; formed 'in fractionat'or`58 is directed from thelowler poriw vtion of 4thiszonethrough .line5'9and valve -60 to pump 6I, by means .of which Lit -is returnedtl'iroughline 62 and'valye 63 to further conver- 'S1011 in heating coil34, together'wththesintermediate .fractions Aof [the charging stook.Supplied $.59

,.thereto, as previously described."

Fraotionated vapors jof the desired Aend-boiling point 'are withdrawn,together with" gaseous con- Version products. of the process; from the,upper portion of vifractionator 58 and directedthrough line "64 andvalvefBE to condensation andcooling in condenser 66. 4Theresulting-,distillatedand 'gases pass through line 61 and valve 68,16.c01- lecton .and separation in 'receiver-QGS, 'Therlistillate,preferably .comprising v gasolirfie of goodigo antiknock value, mayV bef removed from; recenter anydesirecl further-treatment. The uncondensedlgases @may tbe released from the greeeiver x69 65 throughline12anjd-valve 13.

Wheni'desired,jregulatedquantitiesf thadistfillate collected in receiverB 9 :ma-y. be-1- reirculated, :byfwellknown means net illustratfed,toman-PESI' portionv`4 of .fractionator 58 :to :serve las a reeling 17okand- A refluxingf-mediumfin this-r zene. .when desiredthis l samewellaknown expedient. .marche utilized f for controlling L fractionationin i colum the.,v disyIil.zby:returning regulated Quantities@rtillateeollected-inzre@eiser .itnofthaupnersmmen as thereof, by Well-kno'wn means, not illustrated.

characteristics of and substantially The preferred range of operatingconditions, which may be employed in conducting the process in anapparatus such asiillustrated and above described, may be approximatelyas follows:

The temperature to whichthe charging stock is -heated for the purpose ofeffecting its fractional distillation may range, for example, from`450to 700-F. or more, depending primarily upon the the charging stock`employed and the pressure utilized` in the distilling Zone. Any desiredpressure ranging from substantially atmospheric to a superatmosphericpressure of 100 pounds or more per square inch, may be employed in theheating coil of the distilling step the lsame or lower pressure may beutilized in the distilling and fractionating column. In most cases, thedistilling operation is conducted at substantially atmospheric pressureand the charging stock is heated prior to its introduction into thedistilling column to a temperature of from 550 to '700 The temperatureto which vfractions of the charging stock andthe intermediate liquidconversion products of the process Vare heated, as measured at theoutlet from the yheating coil wherein these materials are subjected toconversion in commingled state, may range, for example, from 900 to 975F. or thereabouts= preierably with a superatmospheric pressure at thispoint in the system of from 100 to 500 pounds or more per square inch.

The superatmospheric pressure employed in the reaction chamber mayrange, for example, from 100 yto 500 pounds or thereabouts per squareinchand, as previously mentioned, may b-e substantiallythe same orsomewhat lower as that employed in the communicating and heating coilutilizing the lowest pressure.

Ihe heating coil to which said selected lowboiling fractions of thecharging stock are supplied, may employ an outlet conversion temperatureranging, for example, from 950 to 1050 F. or thereabouts, preferablyWithqa superatmospheric pressure at this point in the system of from 200to 800 pounds or more per square inch.

'I'he `vaporiaing `or coking chamber succeeding the reaction chamber,preferably, as previously mentioned, is operated ata substantiallyreduced pressure relative to that employed in the reaction chamber,which may range, for examplafrom a superatmospheric pressure of 150pounds or thereabouts per square inch down to substantially atmosphericpressure and this pressure may be either substantially cqualized orreduced in the succeeding fractionating, condensing and collectingportions of the cracking system.

As a specic example of an operation of the processV conducted in anapparatus such as illustrated and above described: The charging stock isa mixed base crude of about 28 A. P. I. gravity. containingapproximately 31% of straight-run gasoline boiling up to 437 F. whichincludes approximately 17%, based on the charging stock, of gasolinefractions of good antiknock value boiling up to approximately 300 F. Thecharging stock is heated to a temperature of about 650 F. at asuperatmospheric pressure of about'75 pounds per square inch and theheated oil is introduced into a distilling and fractionating columnoperated at' substantially atmospheric pressure wherefrom the gasolinefractions of the crude boiling up toapproximately 300 F. are recoveredas overhead distillate. Other low-boiling components-oi lthe chargingstock, comprising heavy gasoline and naphtha .fractions amounting toapproximately 23% of the charging stock and having an end-boiling pointof approximately 520 are separately removed asia side-stream from thedistilling and fractionating column and supplied to the light oilcracking or reforming coil yof the system.. Intermediate fractions,comprising an additional `3'0% lor' thereabouts of the charging stock,are separately recovered as a side- .The coil to which said intermediatefractions are supplied employs an outlet conversion temperature ofapproximately 950 F. and a superatmospheric pressure,'measured at theoutlet from this zone, of approximately 350 'pounds per square inch,which pressure is substantially equalized in the reaction chamber toWhich the heated products from this zone are supplied. The light oilcracking or reforming coil is operated at an atmospheric pressure ofapproximately 750 pounds per square inch, as measured at the outlet fromthis Zone, and the temperature of the heated products dischargedtherefrom is approximately 990 F. Approximately 65% of the heatedproducts from the last mentioned coil are supplied to the reactionchamber and the remaining 35% or thereabouts are introduced Lintoalternately operated coking chambers to Whichboth vaporus and liquidconversion products from the reaction chamber are supplied. 'I'hevaporous'components of the commingled materials supplied 'to thereaction chamber lare aiiorded a longer conversion time than theirliquid components zone by supplying all of said materials to the upperportion of the reaction chamber and removing the same in commingledstatefrom its `lower portion to the coking zone. Vaporous products fromthe coking zone are subjected t'o'fractionation and theitotal reuxcondensate resulting from said fractionation is returned for furthercracking to the same heating coil to which said intermediate fractionsof the charging stockare supplied. The coking zone is operated at anat;- mospheric pressure of approximately 80 pounds per square inch andthis pressure is substantially equalizedin the succeeding fractionating,condensing and collecting portions of the cracking system. Thisoperation will produce approxi.- mately 68%, based on the crude chargingstock, of 400 F. end-point gasoline. 'The final gasoline product, whichis a blend of that produced by the cracking and reforming operationswith the straight-run fractions recovered from thetopping step, hasanoctane number of more thanA 70 by the motor' method. yThe additionalproducts of the process comprise approximately GBpounds of good qualitypetroleum coke and approximately 650 cubic feet of rich uncondensiblegas per barrel of crude charging stock.

I claim as my invention:

l. A process ior the treatment of hydrocarbon oils'which comprisessubjecting raw oil charging stock for the process to fractionalAdistillation and thereby separatingthe same into selected lowboiling,intermediate and high-boiling fractions, heating said intermediatefractions to cracking temperature at superatmospheric pressure in aheating coil, -introducing the resulting heated Alzvroducts-into anenlarged lreactionchamber, re-

covering any" components of said low-boiling" dependently of thechargingstock for thenformafractions which boil Within the range of'gasoline tion of a single reflux condensate containing suband aire offsatisfactory antiknock value, heating stantially all components of saidvaporous prodtheremaindery ofI said low-boiling fractions, inuctsheavier than gasoline, subjecting fractionvcluding any: gasolinecomponents ofthe chargingv ated vapors ofthe desired end-boiling pointto '5 stock vvnich are-- of unsatisfactory antiknock condensation,recovering the resulting distillate value, to a higher crackingtemperature at suband returning the total reflux condensate formedstantial super-atmospheric pressure in a separate by said fractionationto the first mentioned heatheating coil, introducing at least a portionofthe i ing coil for further cracking.

4 resultant highly heated products into saidy reac- 3f. A process .suchas `defined in claim l wherein' 10 tion chamber,ccmminglingsaidhigh-boiling regulated quantities of the highly heatedprodfractions' of the charging stock, without previ ucts from saidseparate heating coil are directly ously heatingy the same to crackingtemperature, eemmingled With 'the liquid bi'OfllCtS undergoing with theheated products supplied to said reacvaporization in said Zone ofsubstantially reducedtion chamber and maintaining the commingledpressure and assist in reducing the latter to sub-v 15 materials in saidreaction chamber1 at a sufii- Siani'fieiliy dfi? @Oke in this Zone.

cientlyl high cracking temperature' andi superat- 4. A process such asdefined in claim `l wherein mospheri'c pressure to effectI appreciablecracking VapOrOIlS and liquid COIlVeiSiOI- products are of saidhigh-boiling fractions in this zone, remov- Withdrawn in commineledstate from said` reacing the resulting vaporous and liquid conversiontion chamber and' introduced into saidaone of 20 products from thereaction chamber, subjecting substantially-reduced pressure.'

ization in a zone of substantially reduced presoils which comprisessubjecting raw oil charging Sure relative t0 that employed; in thereaction stock forjthe process to fractional distillationandthe liquidproducts to appreciable Vfurther vapor- 5. A' PIOCeSS for thetreaimenlrO- hydrocarbon ii'chamber, subjecting the vaporcus conversionthereby Separating the Same inte Seleeted 10W 25 products,includihgthoseresulting from said furboiling; intermediate andhigh-boiling fractiene, ther vaporization of the liquid products, tofracheating asid intermediate fractions to cracking tionationindependently of the charging stock for temperature at SlipeleimOSpheriCDYeSSlle in a the formation of a singlereux condensate conheating`COil,V iIlIOlilleiYlg the IeSllitIlg heated taining substantially allcomponents of said va- PlOdilCiiS iiliiO an enlarged reaction Chamber,leporous products heavier than gasoline, subjecting covering anycomponents ofA said low-boiling fractionated vapors of the desiredend-boiling fractions which boil Within the range of gasoline point tocondensation, recovering the resulting and are of satisfactory antiknockvalue, heating distillate and returning said reflux condensate theremainder of said low-boiling fractions, informed by said fractionation,including intermecluding any gaSOlii'le Components 0f the Charging 35diate liquid conversion products boiling above the steek which are 0funsatisfactory antikneck value, range of said intermediate fractions ofthe chargto a higher cracking temperature at substantial ing stock, tothe first mentioned heating coil for superatmospheric pressure in aseparate heating further cracking. coil, introducing at least a portionof the result- 2. A process for the treatment of hydrocarbon ant highlyheated products into a separate en- 40 oils which comprises subjectingraw oil charging larged chamber operated at substantially reduced stockfor the process to fractional distillation and pressure relative to thatemployed in said reaction thereby separating the same into selectedlowchamber, commingling said high-boiling fractions boiling,intermediate and high-boiling fractions, of the charging stock, withoutpreviously heating heating said intermediate fractions to cracking thesame to cracking temperature, With the temperature at superatmosphericpressure in a heated products supplied to said reaction chamu heatingcoil, introducing the resulting heated ber and maintaining thecommingled materials products into an enlarged reaction chamber, reinsaid reaction chamber at a sufficiently high covering any components ofsaid low-boiling cracking temperature and superatmospheric fractionswhich boil Within the range of gasoline pressure to effect appreciablecracking of said and are of satisfactory antiknock value, heating.high-boiling fractions in this zone, removing the the remainder of saidlow-boiling fractions, inresulting vaporous and liquid conversionproducts cluding any gasoline components thereof of the from thereaction chamber, subjecting the liquid charging stock which are ofunsatisfactory antiproducts to appreciable further vaporization knockvalue, to a higher cracking temperature at by supplying the same to saidseparate chamber, i substantial superatmospheric pressure in asepsubjecting the vaporous conversion products, inarate heating coil,introducing at least'a portion cluding those resulting from said furthervaporof the resultant highly heated products into said ization of theliquid products to fractionation i--- reaction chamber, commingling saidhigh-boiling dependently of the charging stock for the formafractions ofthe charging stock, Without prevition of a single reflux condensatecontaining ously heating the same to cracking temperature, substantiallyall components of said vaporous with the heated products supplied tosaid reaction products heavier than gasoline, subjecting fracchamber andmaintaining the commingled matetionated vapors of the desiredend-boiling point rials in said reaction chamber at a sufficiently tocondensation, recovering the resulting distilhigh-crackng temperatureand superatnloslate and returning said reux condensate formed phericpressure to effect appreciable cracking of by said fractionation,including intermediate said high-boiling fractions in this Zone,removingv liquid conversion products boiling above the range theresulting vaporous and liquid conversion of said intermediate fractionsof the charging products from the reaction chamber, subjecting stock, tothe first mentioned heating coil for furthe liquids products toappreciable further vaporther cracking. ization in azone ofsubstantially reduced pressure 6. A process for the treatment ofhydrocarbon relative .to that employed in the reaction chamber, oilswhich comprises subjecting raw oil charging subjecting the vaporousconversion products, instock for the process to fractional distillationand cluding those resulting from said further vaporithereby separatingthe same into selected low- Zation of the liquid products, tofractionation inboiling, intermediate and high-boiling fractions, 75

subjecting said intermediate fractions to cracking ucts and from said'high-boiling fractions ofthe conditions of elevated temperature andsuperatcharging stock in said zone of substantially remospheric pressurein a heating coil and commuduced pressure, to fractionationindependently of nicating enlarged reaction chamber, removing thecharging stock for the formation of a single the resulting vaporous andliquid conversion rei-lux condensate containing substantially all 5products from the reaction chamber, subjecting components of saidvaporous products heavier the liquid products to appreciable furthervaporthan gasoline, subjecting fractionated vapors of ization in a zoneof substantially reduced presthe desired end-boiling point tocondensation, resure relative to that employed in the reaction coveringthe resulting distillate and returning 10 chamber, supplying saidhigh-boiling fractions of said reiiux condensate formed by saidfraction- 10 the charging stock, without previously heating ation,including intermediate liquid conversion the same to crackingtemperature, to said zone of products boiling above the range of saidintersubstantially reduced pressure, recovering any mediate fractions ofthe charging stock, to the components of said lo -boiling fractions ofthe first mentioned heating coil for further cracking. gasoline and areof satisfactory antiknockvalue, said liquid conversion products and saidhighheating the remainder of said low-boiling fracboiling fractions ofthe charging stock are re-` tions, including any gasoline components ofthe duced to coke in said zone of substantially reduced charging stockwhich are of unsatisfactory antipressure. knock value, to a highercracking temperature at 8. A process such as defined in claim 6 wherein20 heated products into said zone of substantially tion chamber andsupplied to said zone of subi reduced pressure, subjecting the totalvaporous stantially reduced pressure. i conversion products of theprocess, including the vapors evolved from said liquid conversion prod-CHARLES H. ANGELL.

charging stock which boil Within the range of 7. A process such asdefined in claim 6 wherein 15 1

